This invention relates to full revolution clutch mechanisms for cyclic machines such as power presses and the like wherein the clutch, after a cycle of operation is initiated by engagement of the clutch parts, automatically releases at the end of a cycle of operation.
A representative mechanical clutch mechanism of the type here under consideration is shown in Munschauer U.S. Pat. No. 2,057,905, dated Oct. 20, 1936. In this prior art mechanism selective means are provided for the operator to run the press either in a continuous or single stroke mode. In the single stroke mode means are provided so that if the operator fails to release the clutch, single stroke mechanism comes into play for insuring disengagement of the clutch at the end of such cycle of operation.
In modern practice using two hand tripping devices, the ability to select continuous operation has been eliminated. The mechanical foot treadle means of clutch actuation has been eliminated and replaced by electric run buttons which require the use of both of the operator's hands to initiate a cycle of operation. The electric control circuitry associated with the two run buttons provides for simultaneous actuation of both buttons, non-tie-down of the buttons and single stroke. The mechanical single stroke mechanism in the aforesaid prior U.S. Pat. 2,507,905 is retained as a back-up device but in a modified form. Should the mechanical single stroke mechanism be caused to function as a back-up device, a latch is released upon such operation of the mechanical single stroke mechanism which prevents reactivation of the cycle-initiating means by the operator and requires the services of a maintenance man at the clutch mechanism to restore the clutch-initiating and single stroke mechanism to operating condition.